linux-kernel - Re: [RFC PATCH v4 3/7] libbpf: Optimize type lookup with binary search for sorted BTF

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Message-ID: <a2aa0996f076e976b8aef43c94658322150443b6.camel@gmail.com>
Date: Tue, 04 Nov 2025 16:19:19 -0800
From: Eduard Zingerman <eddyz87@...il.com>
To: Andrii Nakryiko <andrii.nakryiko@...il.com>, Donglin Peng
	 <dolinux.peng@...il.com>
Cc: ast@...nel.org, linux-kernel@...r.kernel.org, bpf@...r.kernel.org, Alan
 Maguire <alan.maguire@...cle.com>, Song Liu <song@...nel.org>, pengdonglin
 <pengdonglin@...omi.com>
Subject: Re: [RFC PATCH v4 3/7] libbpf: Optimize type lookup with binary
 search for sorted BTF

On Tue, 2025-11-04 at 16:11 -0800, Andrii Nakryiko wrote:

[...]

> > @@ -897,44 +903,134 @@ int btf__resolve_type(const struct btf *btf, __u32 type_id)
> >         return type_id;
> >  }
> > 
> > -__s32 btf__find_by_name(const struct btf *btf, const char *type_name)
> > +/*
> > + * Find BTF types with matching names within the [left, right] index range.
> > + * On success, updates *left and *right to the boundaries of the matching range
> > + * and returns the leftmost matching index.
> > + */
> > +static __s32 btf_find_type_by_name_bsearch(const struct btf *btf, const char *name,
> > +                                               __s32 *left, __s32 *right)
> 
> I thought we discussed this, why do you need "right"? Two binary
> searches where one would do just fine.

I think the idea is that there would be less strcmp's if there is a
long sequence of items with identical names.